Double-acting press with hydraulically coupled hammer and anvil

ABSTRACT

A double-acting press with hydraulic coupling of upper and lower rams has an upper ram connected with a pair of pistons that extend into a closed oil-filled vessel. At least one other piston extends from this vessel up against a lower ram so that descent of the upper ram causes lifting of the lower ram. The piston rods of these pistons can all be inclined to the displacement axis of the rams to twist these rams into engagement with opposite guides and ensure their engagement in a fixed orientation of the forming surfaces. Two pistons can act upon the lower ram in which case the torque can be produced by using pistons of greater effective surface area to one side of the rams. Alternatively a pair of vessels can be provided, one to each side with a respective pair of pistons, and a pump can be provided to maintain the pressure in one vessel above that in the other. The guides can be two pairs of guides for each ram, one pair being above and laterally offset from the other.

United States Patent [1 1 Zimmer et al.

[ DOUBLE-ACTING PRESS WITH HYDRAULICALLY COUPLED HAMMER AND ANVIL [75] Inventors: Kurt Zimmer, Hueckeswagen;

Wilhelm Schneider, Dhuenn, both of Germany [73] Assignee: Beche & Grohs Gmbl-l,

l-luckeswagen/Rhld, Germany 22 Filed: Mar.2, 1971 211 Appl.No.: 120,083

7/1967 Bakhtar 72/407 Dec. 25, 1973 3,429,174 2/1969 Fracke 72/407 Primary Examiner-Charles W. Lanham Assistant Examiner-Gene P. Crosby Attorney-Karl F. Ross [5 7] ABSTRACT A double-acting press with hydraulic coupling of upper and lower rams has an upper ram connected with a pair of pistons that extend into a closed oilfilled vessel. At least one other piston extends from this vessel up against a lower ram so that descent of the upper ram causes lifting of the lower ram. The piston rods of these pistons can all be inclined to the displacement axis of the rams to twist these rams into engagement with opposite guides and ensure their engagement in a fixed orientation of the forming surfaces. Two pistons can act upon the lower ram in which case the torque can beproduced by using pistons of greater effective surface area to one side of the rams. Alternatively a pair of vessels can be provided, one to each side with a respective pair of pistons, and a pump can be provided to maintain the pressure in one vessel above that'in the other. The guides can be two pairs of guides for each ram, one pair being above and laterally offset from the other.

8 Claims, 3 Drawing Figures INVENTORS; K- ZIMMER SCHNEIDER SHEET 30F 3 PATENTEU an: 2 5 I975 I I I I i w CONTROL MEANS l DOUBLE-ACTING PRESS WITH HYDRAULICALLY COUPLED HAMMER AND ANVIL l. Field of the Invention The present invention relates to a double-acting press, especially a forging press of the counteracting type in which an upper ram or hammer and the lower ram or anvil are hydraulically coupled for joint movement toward and away from one another. More specifically this invention concerns such a press wherein a hydraulic link is provided to lift the bottom ram to meet .the descending upper ram.

2. Background of the Invention There is known a press-of the type described wherein a closed vessel filled with liquid is provided below an upwardly displaceable ram. A downwardly displaceable ram is provided with at least two vertical piston rods carrying at their lower ends pistons received in cylinders communicating with the vessel. Another piston in a cylinder communicating with this vessel has a piston connected through a piston rod to the lower ram. As the upper ram is driven downwardly fluid pressure forces the lower ram up.

It is very important that the rams strike each other flatly, i.e. that their confronting surfaces are in a predetermined orientation at the moment of impact. To this end the press is provided with guides for the rams.

Since such presses are often used with hot metals, the rams, which themselves can weigh up to 150 tons apiece and may be displaceable between opposing guides having a spacing of say 1,500mm, must be received with a play of around 1 to 2 millimeters to allow for the expansion and contraction encountered when workpieces of up to tons are worked. The rams heat up to 100C in many cases.

, Because of this play in the guides, the rams often tilt or cant in favor of the preponderant force vector and strike each other unevenly. As long as they both tilt in the same direction to the same extent, the tilt is inconsequential; but when the tilt is in the opposite direction, the workpiece can be ruined. In the usual case the rams tilt to opposite sides more or less arbitrarily.

Summary of the Invention It is an object of the present invention to provide an improved press of the above-defined general type.

Another object is the provision of a press in which the rams approach each other in a mutually parallel relation.

The above objects are attained by a press provided with means for urging the rams preferentially into engagement with one side of the guide so that their surfaces are parallel to each other as they engage. This is achieved by applying a torque in the same direction to each of the rams, which are received with equal play in their guides. In this manner they will be tipped to the same extent in the same direction and, therefore, have parallel surfaces.

According to another feature of the invention, this effect is obtained by structuring the press so that the force-transmitting member or piston rod that raises the lower ram and at least one of the piston rods extending from the upper to the lower ram both are inclined to the press central axis in the same direction. A component of force is thereby produced in each of the rams transverse to this axis.

In accordance with another feature of the present invention two pistons are provided to lift the lower ram, and all of the various pistons and piston rods are parallel to the vertical axis of displacement. The torsion is produced by an unbalance in the forces between the side pistons. This unbalance can be produced by dimensioning the pistons differently, or providing them in independent closed vessels between which a pum is effective to maintain a higher pressure in one vessel than in the other.

This arrangement causes the two rams to be twisted into engagement with opposite guides at opposite ends. Since they are both thus canted in the same direction, their surfaces will engage each other flatly. In addition, since both rams tend to heat up and expand similarly, changes in size are automatically compensated.

Brief Description of the Drawing The above and other objects, features and advantages will become apparent from the following description, reference being made to the accompanying drawing, in which:

FIG. 1 is a side sectional view through a first embodiment of the present invention;

FIG. 2 is a side sectional view through a second embodiment of the present invention; and

FIG. 3 is a side sectional view through a third embodiment of the present invention.

Specific Description As seen in FIG. 1, a straight-sided double-acting press has a frame 1 surrounding an upper ram 2 and a lower ram 3. The upper ram 2 can be formed at its upper end with a piston 4 loosely received in a cylinder 5 whose side walls 6 and 7 act as guides receiving this piston 4 with substantial play. .A reversible variabledisplacement oil hydraulic pump 8 is connected to the cylinder 5 to move the piston 4 up and down; alternatively, the upper ram may be coupled with a flywheel via a unirotational clutch as is common with forging presses. Thelower endof the ram 2 is received with play between apair of fixed guides 9 and 10 which are spaced apart by the same distance W as the guides 6 and 7, are parallel to these guides 6 and 7 but are laterally offset therefrom so that it is impossible that the ram 2 will ever ride simultaneously on either the guides 7 and 10 or the guides 6 and9. The ram 2 is provided with a hammer 11 having a lower surface 12.

The lower ram 3 has a hammer 13 with an upper surface 14 and is similarly received between parallel but laterally offset sets of guides 15-18. The surfaces 12 and 14 are engageable for forging, swaging, drawing or similar metal-working, operations.

To each side of the hammer 11 the upper ram 2 is formed with bores 19 and 20 in which respective rotatable sleeves 21 and 22 having respective offcenter bores 23 and 24 are received. Rotation of the sleeves 21 and 22 determines how much torque is applied to the upper ram 2 as will be described below. A pair of slideable rods 25 and 26 having crowns 27 and 28 are received in the bores 23 and 24, with belleville washers 30a between the crowns 27 and 28 and the sleeves 21 and 22. The rods 25 and 26 are formed at their lower end with respective sockets 29 and 30 receiving the .upper ends of tie rods 31 and 32 whose lower ends bear on sleeve pistons 33 and 34. A closed vessel 35 filled with oil and formed with a pair of vertical cylinder extensions 36 and 37 slidably receiving the pistons 33 and 34. This vessel 35 extends across under the ram 3 and is formed with a third vertical cylindrical extension 38 slidably receiving another sleeve piston 39 formed with a socket 40 receiving the lower end of a piston rod 41.

The upper end of the rod 41 is received in a socket 42 formed in a rod 43 in turn received in an offcenter bore 44 of a sleeve 45. This rod 45 is formd with a crown 46 which bears through a plurality of resilient washers 47 on the sleeve 45. Once again, rotation of the sleeve 45 adjusts the extent to which the point of application of the force is offset from the ram central axis or the extent of inclination of the piston rod 41.

As the pump 8 forces hydraulic fluid into the chamber the ram 2 is therefore driven downwardly. This forces the pistons 33 and 34 down also and causes the piston 39 to rise, lifting the ram 3.

FIG. 1 shows the centers of mass of the two rams 2 and 3 at S, and S, respectively. These points are in line one above the other along a vertical axis A. Each of the 1 pistons 33 and 34 are centered on respective axes 48 and 49 equispaced at a distance D from the axis A. The bores 23 and 24 in the sleeves 21 and 22 are offset by equal distances e, and e, from these axes, however, or as determined by the angular settings of these sleeves 21 and 22. This offsetting creates a component of force P, which is transverse to the axis A and tends to twist the ram 2 about its center S of mass, thereby bringing it into contact with the guides 6 and 10 only.

At the same time the rod 43 is offset to the piston 39 by a similar distance e5 so that a similar torque is applied to the ram 3, bringing it into contact with the guides and 18.

In this manner, even though the rams 2 and 3 are received with significant play in their guides, they are subjected to unbalanced forces which cause them to contact only two guides apiece. It is of course possible to provide a single guide to each side of each ram, the offset guides being uses here so that the application of torque will actually make the two surfaces 12 and 14 horizontal. Any expansion or contraction of the rams 2 and 3 will be of not matter sincetheir relative angle will remain the same, so that they will always come together flatly.

The reference numerals of FIG. 1 are used in FIG. 2 wherever applicable, identical structure being given identical numerals.

The significant difference in the embodiment of FIG.

.2 is that the rods and 26' are in line with the pistons 33 and 34 respectively, and the piston rods 31 and 32 are parallel to the axis A, but the piston 33 is of smaller effective surface area then the piston 34. In addition, a pair of pistons 39a and 39b is provided with piston rods 41a and 41b seated in rods 43a and 43b, respectively. The piston 39a, on the same side of the press as the piston 33', is of smaller effective surface area than the piston 39b and the tie rods 41a and 4122 are parallel to the axis A.

In this embodiment the component of force resulting in a torsion in the rams 2' and 3' about their centers 8 and S is due to the fact that the forces exerted by the pistons 34 and 39b are larger than those of the pistons 33 and 39a. The larger back pressure of the piston 34' applies torque to the ram 2' and the larger forward force exerted by the piston 39b similarly twists theram 3'.

In FIG. 3 structure identical to either FIG. 1 or FIG. 2 is given the same reference numerals.

This embodiment has a pair of pistons 39a and 39b like the embodiment of FIG. 2. However, these pistons are of identical effective surface area, as are the pistons 33 and 34. Rods 25' and 26', and 43a and 43b as in FIG. 2 are provided such that the piston rods 31, 32, 41a and 41b are all parallel to the axis A. Instead of a single vessel, a pair of closed vessels 35a and 35b are provided, the former serving as fluid link between the pistons 33 and 39a and the latter between pistons 34 and 39b.

A fluid pump and a differential-pressure valve 51 are provided between the two vessels 35a and 35b and are connected with the pump 8 to control means 52.

In operation, the control 52 actuates the pumps 8 and 50 simultaneously, while the valve 51 maintains a regular pressure differential. The pump 50 thus causes the pressure in chamber 35b to exceed that in chamber 35a, so that, as seen in FIG. 3, the right-hand side of ram 2 is resisted more by the piston 34 than the lefthand side is resisted by the piston 33 and the right-hand side of the ram 3" is similarly twisted. This application of torque brings the two rams 2" and 3" into contact with their respective guide surfaces 6, 10 and 15, 18, to line the two surfaces 12 and 14 up parallel to each other. For disengagement of the two rams, the control means 52 reverses the pump 8 and stops the pump 50.

It can be seen that with all three embodiments the forces applied to the rams are unbalanced in such a manner as to hold them in a like position in their respective guides. Since it is out of the question to provide tight guides for these rams because of their frequent expansion and contraction, the solution of the present invention ensures that they meet flatly in a simple manner.

Of course, it is impossible to form combinations of any of the above-described embodiments. For instance, the pair of pistons flanking the upper ram can be operative along axes inclined to the machine-closing axis, as in FIG. 1, but a pair of pistons of different effective cross-sections can be used to twist the lower ram, as in FIG. 2. It would not be impossible to change the embodiment of FIG. 1 by eliminating the hydraulic link and providing a pair of lever, or a toggle arrangement to raise the lower ram on lowering of the upper arm. All such embodiments are understood to form part of the present invention and to be included in its scope.

We claim:

1. A double-acting press comprising:

a vertically displaceable upper ram having a lower surface; a vertically displaceable lower ram having an upper surface engageable with said lower surface;

respective pairs of upright guides laterally receiving and flanking opposite sides of said rams with play; and

hydraulic link means between said rams for reciprocally displacing same and for applying torque to said rams in the same sense to urge each of same preferentially against one side of each of said guides and thereby ensure flat engagement of said surfaces with each other.

2. The press defined in claim 1 wherein said link means includes at least a first, second and third piston and at least one closed vessel filled with a fluid in contact with all three pistons and operatively interconnecting same, the first and second pistons flanking and being operatively connected to one of said rams at opposite sides thereof and the third piston being operatively connected to the other ram.

3. The press defined in claim 2 wherein said rams are displaceable along a vertical axis, said means for applying torque including at least one elongated forcetransmitting member having one end bearing on one of said pistons at a first location and another end bearing on a one of said rams at a second location, said first and second locations defining a member axis extending at an angle to said vertical axis.

4. The press defined in claim 3, further comprising means for varying the inclination of said member axis relative to said vertical axis.

5. The press definedin claim 4 wherein said means for varying the inclination includes a sleeve rotatable about a sleeve axis and having a socket receiving said other end of said elongated member, said socket being eccentric with respect to said sleeve axis.

6. The press defined in claim 3 wherein each of said pistons has such a force-transmitting member defining a member axis inclined to said vertical axis, said member axes all being inclined in the same direction.

7. The press defined in claim 2 wherein said link means includes a fourth piston operatively connected along with said third piston to said other ram, said third and fourth pistons being disposed next to each other, said first and third pistons being disposed to the same side of said rams and being of greater effective surface area than said second and fourth pistons.

8. The press defined in claim 1 wherein each of said pairs of guides has an upper set of parallel guides and a lower set of parallel guides, said upper set being out of line with said lower set and offset therefrom to maintain said surfaces horizontal. 

1. A double-acting press comprising: a vertically displaceable upper ram having a lower surface; a vertically displaceable lower ram having an upper surface engageable with said lower surface; respective pairs of upright guides laterally receiving and flanking opposite sides of said rams with play; and hydraulic link means between said rams for reciprocally displacing same and for applying torque to said rams in the same sense to urge each of same preferentially against one side of each of said guides and thereby ensure flat engagement of said surfaces with each other.
 2. The press defined in claim 1 wherein said link means includes at least a first, second and third piston and at least one closed vessel filled with a fluid in contact with all three pistons and operatively interconnecting same, the first and second pistons flanking and being operatively connected to one of said rams at opposite sides thereof and the third piston being operatively connected to the other ram.
 3. The press defined in claim 2 wherein said rams are displaceable along a vertical axis, said means for applying torque including at least one elongated force-transmitting member having one end bearing on one of said pistons at a first location and another end bearing on a one of said rams at a second location, said first and second locations defining a member axis extending at an angle to said vertical axis.
 4. The press defined in claim 3, further comprising meAns for varying the inclination of said member axis relative to said vertical axis.
 5. The press defined in claim 4 wherein said means for varying the inclination includes a sleeve rotatable about a sleeve axis and having a socket receiving said other end of said elongated member, said socket being eccentric with respect to said sleeve axis.
 6. The press defined in claim 3 wherein each of said pistons has such a force-transmitting member defining a member axis inclined to said vertical axis, said member axes all being inclined in the same direction.
 7. The press defined in claim 2 wherein said link means includes a fourth piston operatively connected along with said third piston to said other ram, said third and fourth pistons being disposed next to each other, said first and third pistons being disposed to the same side of said rams and being of greater effective surface area than said second and fourth pistons.
 8. The press defined in claim 1 wherein each of said pairs of guides has an upper set of parallel guides and a lower set of parallel guides, said upper set being out of line with said lower set and offset therefrom to maintain said surfaces horizontal. 